Doug Williams tells a story: When he met Walter Payton's mother she told him that as she watched the Redskins play the Bears she began rooting against her son's team and started cheering for Doug Williams to win. Why? According to Williams the answer is "obvious."

Doug Williams is obviously black and obviously there have been few black quarterbacks in the National Football League. And today, when he leads the Redskins on the field for the Super Bowl, Williams will be the first black quarterback to start in pro football's marquee game.

Black or white, football fan or not, the sight of Williams under center as a starting quarterback is heavily laden with emotion for many people. Even for those hardcore football fans who don't want to think about social issues like race-relations, it is difficult to turn a blind eye to the fact-and significance-of Williams' breakthrough today.

This event is nowhere near the importance of Jackie Robinson's daring entrance into major league baseball. Robinson's arrival in 1948 signalled the coming of seimic social changes in the nation for the next decade-the desegregation of schools, lunch counters and voting booths. Doug Williams as a Super Bowl quarterback is not Jackie Robinson revisited and people who heap that load on him are straining him as well as their own credibility.

But in 1988, Williams' presence in San Diego has its own ramifications for a nation still struggling with race. In a phrase, what Doug Williams means is that "Blacks Can Do It." He is wiping out the lie that said an NFL team can't win big games with a black quarterback because blacks are not smart enough and incapable of being the mentally tough leader who inspires teammates in the crunch.

Countless good black college quarterbacks have been told to play defensive back or wide receiver in the NFL, sent to play in the Canadian League or put out of the game. The explanation for this was never shouted but whispered in polite company behind the coaches door, in the general manager's office and the owner's box: blacks are not smart enough to call the plays, they don't have the quick wits needed to handle audibles and they lack leadership ability. Every explanation was offered but the truth-race.

"There was always an unwritten rule (on black quarterbacks): Are they smart enough? . . ." Bill Nunn, the former Pittsburgh Steeler scout said in an interview last year. "I think it's ridiculous that there have always been those kind of labels."

Football is an essential part of American culture and quarterback is the glamour position in the culture of football. It is a position for the flamboyant (Joe Namath), the good preacher's son (Fran Tarkenton), the brilliant (Bart Starr), the gutty (Johnny Unitas) and even the not-so-smart but talented (Terry Bradshaw). White coaches and owners could put their trust in a leader/quarterback anywhere in that spectrum of personality and talent. But somehow that trust hardly ever extended to men who were black.

Now, as Joe Gibbs put his highest aspiration on the line for a Super Bowl victgory, he hands the ball to a very mature and capable black quarterback. He is going with a man who completed 57 percent of his passes and, if he had played enough games, would be rated the third-best quarterback in the league behind Joe Montana and Bernie Kosar. Gibbs describes Williams as "very much a veteran...he's got great poise about him; I think he is extremely mentally tough and I think he's smart."

That's the breakthrough. Doug Williams is no role player; he is no token player; he did not get his job as a gesture of racial harmonyj. The coach is going with his best quarterback, he is going with a player he believes in and he is doing it despite the hoary folk tales about black quarterbacks choking and not being able to win the big games.

With the increasing number of black collegiate quarterbacks and acceptance of the idea that a running quarterback enhances a pro teams's offense, more black qre black quarterbacks are in the future for the NFL. This season, Warren Moon led the Houston Oilers to the playoffs, and Philadelphia's Randal Cunningham is considered one of the league's rising young stars.

And when black quarterbacks are common, Dough Williams will always be cited as the pioneer who worked through rough times in Tampa (he left after a bitter contract dispute turned racial), hard times in his personal life. (his wife died of a brain tumor) and tough times in the USFL (he was injured) until he showed that blacks had the mental strenght, the leadership and the class to quarterback a team to the Super Bowl.

Juan Williams is a staff writer for The Washington Post Magazine.